Many portable computers, especially hand-held or "palmtop" computers, use integrated circuit memory cards ("IC memory cards") as the primary media of information storage. Such IC memory cards include memory storage elements, such as static random access memory (SRAM), or electrical programmable and erasable non-volatile memory elements, such as "flash" memory. These IC memory cards are typically the size of a customary credit card. IC memory card slots are used in portable computers in place of hard disk drives and floppy disk drives (HDDs, FDDs) to achieve in the portable computer the significant advantages of size, weight, and battery lifetime. In addition, the removeable IC memory cards provide storage media portability. However, because of the limited storage density attainable in each IC memory card, and the high cost of IC memory chips, using IC memory cards in hand-held computers imposes limitations not encountered in less portable computers, which typically use more power-consuming and heavier hard and floppy disk drives as their primary storage media. Also, in order to avoid the sizes and weights of a necessary higher voltage power supply unit and an interface adaptor, a hand-held computer is typically not equipped with a standardized interface (e.g. RS232C) found on the larger desktop and laptop computers. This is because such a standardized interface is larger than can be conveniently provided on such a hand-held computer, and requires both voltage and power output levels impractical for such a hand-held computer, if the requirements of size, weight and long battery lifetime are to be met.
Another disadvantage often found in a hand-held computer using IC memory card as the primary storage media results from the hand-held computer's inability to provide a variety of system services normally available in a larger computer, e.g. connection to a hard copy device, or data transfer to a backup facility to prevent loss of data. Many of these system services are not provided because, for a hand-held computer, a standardized interface to peripheral equipment is too bulky and requires the hand-held computer to generate voltage levels impractical in view of the hand-held computer's size, weight and power conservation requirements. Thus, in the prior art, such a hand-held computer interfaces to a peripheral device through a separate adapter which provides the standard size connector, and the necessary voltage level and signal representation conversions. At present, a number of these adapters are required to provide the various interfaces to common peripheral devices. Such adapters are bulky and cannot be simultaneously connected to the single small I/O connector on the hand-held computer. In addition, each adaptor is connected to the hand-held computer via a customized cable and powered by the power supply of the hand-held computer. Thus, even for performing the most common applications, such as data backup and printing, the hand-held computer requires multiple adapters and each adaptor drains the precious battery power from the hand-held computer. To perform data backup, for example, a popular "PC-link cable" is used to connect the hand-held computer to the RS232C (serial) port of a desk top computer over a customized cable and a bulky attachment. Even then, the PC link cable provides only data transfer capability. Further, to use the PC link cable, the user is required to run a customized software and to set up the desktop computer. To perform printing, a "printer-link cable" connects the hand-held computer to a printer. Again, the connection to the printer requires another customized cable, a bulky adaptor and the use of a customized software. Of significance also, because the PC-link and printer-link cables plug into the same port on the hand-held computer, printing and data backup cannot be performed simultaneously. Further, since the printer-link and PC-link cables are expensive relative to the cost of the handheld computer, customized cables and adapters are very uneconomical ways to provide common applications in the hand-held computer.
Therefore, because of the limited functionalities necessitated by the size, weight and long battery lifetime requirements of a portable computer, the user is often required to transfer data from the portable computer to a desktop computer for such tasks as data backup or printing. The importance of such functions as backing up information or obtaining hard copies is self-evident, once one appreciates that the data most often stored in such computers are, for example, telephone numbers, addresses, memoranda, past appointment schedules, spreadsheets, and databases. Information backups are particularly essential for record keeping and for recovering from an occasional system malfunction.
In addition, because the storage capacity of an IC memory card-based portable computer is limited, it is often necessary to unload some of the stored telephone numbers, address records, or the software and data of one application program to create room for new telephone numbers, address records, or data and software of another application program. Currently, data transfer between the portable computer and the desk top computer is cumbersome and error-prone for the non-expert users. For example, the user may be required to buy both a customized connection cable and a special communication software, and be required to perform a sophisticated set of tasks, such as connecting the cable to a RS232C port on the backplane of a desktop computer, setting up files and operating the communication software from the desktop computer. For many people, the apparent level of required skill to perform these tasks is a psychological barrier to their ability to use the portable computer effectively. Further, the added cost of a desktop computer is often not justified for people who do not otherwise need a desk-top computer.
The resource limitations of a palmtop computer also dictate the use of customized operating systems and file structures in these palmtop computers. These customized operating systems and file structures are impediments to data transfer and software interoperability between the palmtop computers and the more standardized larger systems.
Also, in the past, IC memory cards are formatted in the proprietary formats of the palmtop computer manufacturers. Consequently, IC memory cards used in palmtop computers from different manufacturers are not interchangeable with each other, nor can these IC memory cards be shared between a palmtop computer and a larger desktop computer, where standardization is more prevalent. However, as the PCMCIA (Personal Computer Memory Card International Association) standard becomes more widely adopted, there is a great need for a method whereby data stored in the proprietary formats of the palmtop computers can be exchanged under the PCMCIA format without costly modifications in the palmtop computers.
In the prior art, there are numerous intelligent peripheral devices for such functions as information storage, printout, communication, and input/output (I/O). However, none of these devices integrate these functions into a single device in the manner achieved by the present invention to be described hereinafter.